Knife sharpener



United States Patent KNIFE SHARPENER Charles R. Jahn, Chicago, Ill.

Application September 9, 1954, Serial No. 454,939

6 Claims. (Cl. 51-181) This invention relates to an improved knifesharpener.

One principal object of the invention is to provide an improved knifesharpener capable of being used for sharpening and honing the edge of aknife in successive operations which are easily carried out.

A further object is to provide a knife sharpener having means formaintaining the sharpening and honing elements in optimum engagement.

It is another object of the invention to provide an improved knifesharpener arranged to compensate for wear in the sharpening and honingelements.

A further object is to provide an improved knife sharpener having meanswhereby fresh surfaces of the sharpening elements may be brought intoplay to compensate for wear.

Another object of the invention is to provide an improved knifesharpener which is simple to use, attractive in appearance and low incost.

Further objects and advantages of the invention will appear from thefollowing description, taken with the accompanying drawings, in which:

Figure 1 is an elevational view of an exemplary knife sharpenerconstituting a purely illustrative embodiment of the invention;

Fig. 2 is a plan view of the knife sharpener of Fig. 1;

Fig. 3 is a longitudinal sectional view taken generally along a line 33in Fig. 2;

Fig. 4 is an enlarged fragmentary sectional view taken generally along aline 4-4 in Fig. 1;

Fig. 5 is a fragmentary elevational view taken as indicated by a line5-5 in Fig. 2;

Fig. 6 is a perspective view of a pair of abrasive sharpening wheelsemployed in the knife sharpener;

Fig. 7 is a perspective view of a pair of honing balls embodied in thesharpener;

Fig. 8 is a perspective view of a spring mechanism for biasing thewheels and balls; and v v Fig. 9 is a fragmentary sectional viewillustrating a modified arrangement of the honing balls.

If the drawings are considered in greater detail, they will be seen toillustrate a knife sharpener 10 adapted to sharpen and hone the edge ofa knife. The illustrated sharpener comprises a body 11 having one endformed into a handle 12 adapted to be gripped by the hand of a user.Feet 13 and 14 in the form of rubber or rubberlike grommets are mountedon the underside of the body 11 to support the knife sharpener on atable .or other supporting surface. The grommets 13 and 14are seated inapertures 15 and 16 formed in lower wall elements 17 and 18 of the body11. The body 11 preferably is formed from a resinous plastic material bya molding operation and hence is shown as including a pair of halfshells 19 and 20 joined by cement or by the illustrated screw fasteners21. The body 11 is formed with an enlarged head 22 for supporting thesharpening and honing elements of the sharpener.

in order to provide for the sharpening of a knife, two

engageable abrasive wheels or stones 23 and 24 are mounted in the headend 22 of the body 11. The sharpening wheels 23 and 24 may be made ofany suitable material, such as sintered aluminum oxide, for example. Itwill be seen that the wheels 23 and 24 are cylindrical or roller-shapedin form.

In the illustrated construction, the wheels 23 and 24 are received inrecesses 25 formed in the opposed half shell members 19 and 20. Shafts26 and 27 extend axially through the wheels 23 and 24. The shaft 26 forthe first wheel 23 is rotatably supported in bearing openings 28 and 29formed in the half shells 19 and 20. To provide for lateral translationas well as rotation of the second wheel 24, the shaft 27 is received inelongated slots or bearing openings 30 and 31 formed in the half shells19 and 20. With this construction, the wheel 24 is movable toward andaway from the wheel 23. However, the range of movement of the wheel 24is limited by the recesses 25 so as to prevent a knife from passingbetween the wheels 23 and 24. It will be seen that the recesses 25 areformed with cylindrically curved end portions 32 and 33 having a loosefit with the peripheries of the wheels 23 and 24.

In order to provide for rotary adjustment of the wheels 23 and 24, akerf 34 or other tool engaging element is formed in one end of at leastone of the shafts 26 and 27. In this instance, both of the shafts 26 and27 are formed with the kerfs 34. It will be understood that a screwdriver or other suitable tool may be engaged with either of the kerfs 34to rotate the wheels 23 and 24 and thereby bring new sharpening surfacesinto play. Rotating either of the wheel shafts 26 and 27 will tend torotate both wheels because of the frictional engagement between thewheels. The bearing openings 28 and 30 in the half shell 19 are in theform of apertures extending through the wall of the half shell so as toafford access to the kerfs 34. In the other half shell 20 the bearingopenings 29 and 31 may be in the form of recesses.

For the purpose of honing the edge of a knife, the knife sharpener 10 isequipped with first and second engageable metal balls 36 and 37 receivedin opposed recesses 33 formed in the half shells 19 and 20. It will beseen that the recesses 38 are provided with spherically curved endportions 39 and 40 which limit spreading movement of the balls 36 and 37so that a knife will be prevented from passing completely between theballs.

A spring 41 or other resilient element is provided to bias thesharpening wheels 23 and 24 and the honing balls 36 and 37 together. Inthis instance, the resilient element 41 takes the form of a generallyhelical compression spring acting between arms 42 and 43 of a generallyU- shaped member 44. The upper end of the arm 42 is formed into acylindrically curved portion 45 which engages the periphery of thesharpening wheel 24 and urges the wheel against the other wheel 23. Theupper end of the arm 43 is provided with a portion 46 which engages theball 37 and urges it against the ball 36. In the illustratedconstruction, dimples 47 and 48 are formed in the arms 42 and 43 toretain the opposite ends of the compression spring 41.

In order to admit a knife to the crotches between the wheels 23 and 24and the balls 36 and 37, V-shaped notches 49 and 50 are formed in thebody 11 opposite the wheels and balls to reduce friction between theabrasive wheels 23 and 24 and the body 11 of the sharpener, and therebyfacilitate rotary adjustment of the wheels, the body 11 is formed withbosses 51, 52, 53, and 54 around the bearing openings 28, 29, 30 and 31.These bosses provide clearance between the body 11 and the major portionof the end area of the abrasive wheels 23 and 24.

In use, the knife sharpener is gripped in one hand of the user andpreferably is. held with the feet 13 and 14 against a table or someother supporting surface. The rubber feet prevent the sharpener fromslipping along the table when the sharpener is in use. I

A knife may be sharpened by inserting the cutting edge of the knifethrough the V-shaped notch 49 and into the crotch between the abrasivesharpening wheels 23 and 24. The knife is drawn longitudinally along thecrotch to sharpen the cutting edge. During the sharpening operation, thespring 41 holds the abrasiye'wheels 23 and24 together. If heavy pressureis applied to the knife, the wheels may separate slightly, but theamount of separation is limited by the extent of the recesses 32 so thatthe knife will not pass between the wheels and drag on the plastic body12,

The knife may be honed by inserting its cutting edge into the notch 59and drawing the lunfe longitudinally along the crotch between the honingballs 36 and 37. During this operation, the spring 41 biases the ball 37toward the ball 36. Normally the balls are held in engagement during thehoning operation. Even if considerable pressure is applied to the knife,the recesses 33 in the body 11 prevent any substantial separation of theballs. Accordingly, the knife cannot be pushed between the balls so asto come into engagement with the body 11.

After considerable use, the abrasive sharpening wheels 23 may be wornfiat in the sharpening zone provided by the crotch between the wheels.However, new sharpening surfaces may be brought into play simply byinserting a screw driver or other suitable tool into the kerfs 34 androtating the wheels 23 and 24. The bosses 51, 52, S3, and 54 facilitatesuch rotation by reducing the friction between the wheels and the body11.

The knife sharpener ll) may be manufactured at an extremely low costand, hence, may be marketed on a large scale or even given away as apremium item. The sharpener is not only effective in carrying out its'intended purpose, but also is convenient in use and attractive inappearance.

Fig. 9 illustrates a modified construction in which the balls 36 and 37are received in a pair of recesses 38a formed in the half shell elements19 and of the body 11. In order to maintain the balls in engagement whena knife is pushed downwardly into the crotch between the balls, therecesses 38a are formed with downwardly tapering or converging endsurfaces 39a and 49a. When downward pressure is applied to the balls 36and 37 the converging end surfaces 39a and 40a tend to wedge the ballstoward each other and thereby maintain the balls in intimate engagement.In this way, the balls are prevented from spreading substantially underthe pressure of a knife thrust downwardly into the crotch between theballs. With this modified construction, it is not necessary to utilize aspring or other resilient element to bias the honing balls intoengagement. Accordingly, the right hand leg 43 and the lower portion ofthe member 44- of the construction shown in Fig. 3' are omitted in themodified construction of Fig. 9, leaving only the left hand leg,designated 42a, having a curved portion 45a engaging the sharpeningstone 24. The spring 41 is seated in opposed recesses 41a formed in thehalf shells 19 and 20. The recesses 41a prevent lateral displacement ofthe spring 41 and eliminate any need for a dimple or other springsupporting element on the member 42a.

Various modifications, alternative constructions and equivalents may beemployed without departing from the true spirit and scope of theinvention as exemplified in the foregoing description and defined in thefollowing claims.

I claim:

1. A knife sharpener, comprising abody including a pair of half shellsjoined together, said body having one end portion. formed into a handle,a pair of. rubber-like feet mounted on said body adjacent its oppositeends for engaging a supporting surface, a pair of engageable generallycylindrical abrasive wheels, said half shells having generallycylindrically curved recesses receiving said wheels, said wheels havingshafts extending therethrough, one of said half shells haying apair ofapertures for supporting said shafts at one end thereof, at least one ofsaid safts at one end thereof having a kerf formed therein foradjusting. the angular positions of said wheels, and the other of saidhalf shells having a pair of openings for supporting the opposite endsof said shafts, one of said apertures and one of. said openings beingelongated to provide for lateral movement of one of said wheels towardand away from the other of said wheels, 21 pair of engageable metallichoning balls, said half shells having spherically curved recessesreceiving said balls, said body having a pair of notches formed thereinfor admitting a knife to thecrotches between said wheels and said balls,said cylindrically curved and spherically curved recesses limitingspreading movement of said wheels and said balls to prevent a knife frompassing fully therebetween, a generally U-shaped member having a firstleg engaging one of said wheels and a second leg engaging one of saidballs, and a helical compression spring disposed between said legs forbiasing said one wheel and said one ball against said other wheel andsaid other ball.

2. A knife sharpener, comprising a handle including a pair of halfshells, first and second engageable abrasive sharpening wheels havingfirst and second shafts extending therethrough, first bearing means insaid half shells supporting said first shaft for rotation, secondbearing means insaid half shells supporting said second shaft forrotation and lateral movement toward and away from said first shaft,first and second engageable honing balls arranged in line with saidwheels, said half shells having spherically curved recesses supportingsaid balls, said recesses supporting said second ball for limitedlateral movement toward and from said first ball, and resilient meansacting between said second sharpening wheel and said second ball forbiasing said second wheel against said first wheel and biasing saidsecond ball against said first ball.

3'. A knife sharpener, comprising a supporting body, first and secondabrasive wheels, means for rotatably mounting said first wheel in saidbody, means mounting said second Wheel in said body for rotation andlateral movement toward and away from said first wheel, first and secondhoning bails arranged in line with said Wheels, means rotatably mountingsaid first ball in said body, means mounting said second ball in saidbody for rotation and lateral movement toward and away from said firstball, and resilient means acting between said second wheel and saidsecond ball for biasing said second Wheel against said first wheel whilebiasing said second ball against said first ball.

4. A knife sharpener, comprising a supporting body, first and secondabrasive wheels with engageable pcripheral surfaces, means mounting saidwheels in said body for rotary adjustment and supporting said secondwheel for limited movement toward and away from said first wheel,resilient means biasing said second wheel against said first wheel, andmeans on at least one of said wheels defining a screw driver slot foreffecting rotary adjustment of said wheels.

5; A knife sharpener, comprising a supporting body, first and secondabrasive wheels with engageable peripheral surfaces, means mounting saidwheels in said body for rotary adjustment and supporting said secondwheel for limited movement toward and away from said first wheel,resilient means biasing said second wheel against said first wheel, andmeans on at least one of said wheels defining a tool receiving formationfor efiecting rotary adjustment of said wheels.

6. A knife sharpener, comprising a supporting body, first and secondabrasive wheels, means for rotatably mounting said first wheel in saidbody, means mounting said second wheel in said body for rotation andlateral movement toward and away from said first wheel, first and secondhoning balls arranged in line with said wheels, means rotatably mountingsaid first ball in said body, means mounting said second ball in saidbody for rotation and lateral movement toward and away from said firstball, resilient means acting between said second wheel and said secondball for biasing said second Wheel against said first wheel whilebiasing said second ball against said first ball, and means on at leastone of said wheels defining a screw driver receiving formation forelfecting rotary adjustment of said wheels, said body having an openingfor admitting a screw driver to said formation.

References Cited in the file of this patent UNITED STATES PATENTS1,353,485 McGall Sept. 21, 1920 1,463,653 Loomis July 31, 1923 1,612,323Statts-Oels Dec. 28, 1926 FOREIGN PATENTS 131,130 Great Britain Aug. 12,1919 206,251 Switzerland July 31, 1939 681,766 Great Britain Oct. 29,1952

